Regulatory Capital Requirements - Actual and Statutory Required Capital Amounts and Ratios (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Actual
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Total risk-based capital to risk-weighted assets	$ 229,663	$ 200,835
Tier 1 capital to risk-weighted assets	216,061	188,029
Tier 1 capital to average total assets	216,061	188,029
Total risk-based capital to risk-weighted assets, ratio	21.19%	19.76%
Tier 1 capital to risk-weighted assets, ratio	19.94%	18.50%
Tier 1 capital to average total assets, ratio	12.05%	10.50%
Minimum Capital Requirements Per Regulation
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Total risk-based capital to risk-weighted assets	86,695	81,293
Tier 1 capital to average total assets	71,711	71,611
Total risk-based capital to risk-weighted assets, ratio	8.00%	8.00%
Tier 1 capital to average total assets, ratio	4.00%	4.00%
To be Well Capitalized Under Prompt Corrective Action Provisions
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Total risk-based capital to risk-weighted assets	108,368	101,616
Tier 1 capital to risk-weighted assets	65,021	60,969
Tier 1 capital to average total assets	$ 89,638	$ 89,514
Total risk-based capital to risk-weighted assets, ratio	10.00%	10.00%
Tier 1 capital to risk-weighted assets, ratio	6.00%	6.00%
Tier 1 capital to average total assets, ratio	5.00%	5.00%